Also known as: Super Mario Bros.: The Lost Levels (US/EU) Developer:
Famicom Disk System Released in JP: June 3, 1986 Released in US: May 1, 2007 (Virtual Console) Released in EU: April 14, 2007 (Virtual Console)
The Japanese Super Mario Bros. 2 is basically Super Mario Bros. with the difficulty cranked to 11. The expanded space provided by the disk format allowed for longer and more complex levels, several new gimmicks, and a total of 13 worlds... but overall, it's essentially the same game.
Due primarily to its extreme difficulty and similarity to its predecessor, overseas players wouldn't get the chance to play the game until the release of Super Mario All-Stars, albeit in a remade form. The unlockable version included with Super Mario Bros. Deluxe did not have the unique graphics of the original release, unique stats for Mario and Luigi, or anything normally accessible past 8-4, and non-Japanese gamers did not get to play the original unaltered game until it was released internationally on the Wii Virtual Console.
Two unused ground tiles and a cactus can be found at the very end of the SM2CHAR1 graphics file. The last tile, a more natural-looking variation of the original Super Mario Bros. ground tile, actually appears in every screenshot in the game's manual, suggesting that it was changed very late in development.
In 3-1, a Red Koopa Troopa is placed directly above a pit. It's normally impossible to see this enemy in-game, as by the time the player reaches the screen in question, it's already fallen into the pit. The only way to see it without hacks is to glitch Mario's position to the furthest right side of the screen, then take damage, which causes the screen to scroll to the right and give the player a glimpse of the Koopa as it falls into oblivion.
In 2004, Super Mario Bros. 2 was rereleased as part of Japan's Famicom Mini series for the Game Boy Advance as Famicom Mini vol. 21. The most significant change in this version is that A + Start allows you to, after getting a Game Over, immediately go back to the start of the world you died in (barring Worlds 9 and A-D). This not only renders the "Continue" option redundant, but has some other effects:
Using the emulator's menu (accessible by pressing L + R) to save your high score will also save the last world you died on, meaning the A + Start combo still works even after the game is turned off, which makes it possible to complete the game in multiple sessions.
It is possible to switch between Mario and Luigi mid-game without having to start over, which was not possible in the FDS version.
After beating 8-4 eight times, the player must press B + Start at the title screen to access World A-1 rather than the FDS version's A + Start.
These changes did not carry over to the 3DS, Wii/Wii U, and Switch versions, which instead behave the same way as the original FDS version.